Update the Server project for net9.0+

[dansiegel]

Description

Currently the Server project is making use of legacy APIs for the API Explorer and Swagger

uno.templates/src/Uno.Templates/content/unoapp/MyExtensionsApp.1.Server/Program.cs

Lines 40 to 60 in de938ef

	builder.Services.AddEndpointsApiExplorer();
	builder.Services.AddSwaggerGen(c =>
	{
	// Include XML comments for all included assemblies
	Directory.EnumerateFiles(AppContext.BaseDirectory, "*.xml")
	.Where(x => x.Contains("MyExtensionsApp._1")
	&& File.Exists(Path.Combine(
	AppContext.BaseDirectory,
	$"{Path.GetFileNameWithoutExtension(x)}.dll")))
	.ToList()
	.ForEach(path => c.IncludeXmlComments(path));
	});
	var app = builder.Build();
	// Configure the HTTP request pipeline.
	if (app.Environment.IsDevelopment())
	{
	app.UseSwagger();
	app.UseSwaggerUI();
	}

This should be updated with net9.0 to use the OpenAPI extension and as it seems the more popular one these days is Scalar this should also be updated accordingly.

// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
builder.Services.AddOpenApi();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.MapOpenApi();
    app.MapScalarApiReference(o =>
    {
        o.EnabledClients = [
            ScalarClient.HttpClient,
            ScalarClient.Http11,
            ScalarClient.JQuery,
            ScalarClient.Xhr
        ];
    });
}